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The weapon of the future, the blunderbuss of Buck Rogers, may soon be aimed at the air-fuel mixture inside your “spark-ignition” engine. Yes, after reinventing practically every other element of Old Smokey, the spark plug — virtually identical in its essential form and function to the one patented 111 years ago — may soon be ditched in favor of laser beams.

First let’s examine the case against Sparky. Despite laudable upgrades like long-lived platinum tips, computer-controlled coil-on-plug ignition, and even fancy multispark electrodes, there’s no getting around a few basic drawbacks: The spark gets generated very near the cylinder wall, which complicates cold starts when all that engine metal is frigid and results in lots of heat transfer to the engine and plug. The flame front also has to travel farther for a complete burn of the mixture. Spark-plug electrodes wear, and providing for easy replacement dictates placing the plug right where bigger valves and direct fuel injectors want to be.

Laser ignition promises a way around all these shortcomings. Researchers at Colorado State University began working on laser ignition for heavy-duty natural-gas engines back in 2002, and more recently Ford and the University of Liverpool in the U.K. have teamed up to develop a passenger-car application. Here’s how it works: A near-infrared laser beam shines through a lens that focuses the light at a particular point (or possibly at multiple points) in the cylinder, generating intense energy that causes the air molecules to ionize. This creates a plasma discharge (it looks like a spark formed in mid air) that ignites the air-fuel mixture. Such plasma discharges form in as little as 100 nanoseconds (100 billionths of a second — about as long as it takes the federal government to spend $13). Regular sparks last some 8000 times longer, so it’s possible to create numerous laser plasma blasts during a single combustion stroke. And the laser’s energy is expected to keep the lens blasted clear of soot automatically, so no maintenance is likely to be required. Leaner operation promises greater fuel efficiency, while more complete combustion at lower temperatures should reduce emissions (nobody’s talking percentages yet).

But perhaps the real genius of laser ignition is its ability to diagnose the spent combustion gasses after ignition. By fitting the lens with a receiver to pick up laser light reflected back through the exhaust cloud the engine controller can measure how completely the fuel is burning (particularly during cold starts) or determine what type of fuel was burned (in flex-fuel cars) and adjust accordingly. This added sophistication should help bring homogeneous-charge compression-ignition (HCCI, the gas engine with near diesel efficiency, “Technologue,” December 2007) closer to reality and the ability to produce multiple sparks throughout the cylinder might also help bring ammonia-fueled engines to the fore (“Technologue,” November 2008).

Getting that laser light into the cylinder is tricky. One laser per cylinder would be easy but far too costly. Splitting a single laser source into multiple beams aimed down light pipes with mirrors presents problems with vibration and packaging. Fiberoptic cables are most convenient, but in early trials normal materials lost up to 20 percent of the laser energy in tighter bends and the cables deteriorated rapidly. The Colorado State folks devised special hollow, silver-lined, helium-filled fiber optic wires that seem up to the task.

Those certainly sound pricier than spark-plug wires, and a laser probably rings in higher than a handful of coils. Nobody’s talking price yet, but I expect the incremental cost (and fuel-economy benefit) for laser ignition will be slightly less than that of direct fuel injection. But slap a “Laser-Fired” badge on it, and the Sci-Fi set will happily pony up.